[PATCH v2 03/20] n_tty: Move buffers into n_tty_data

From: Peter Hurley
Date: Sat Jun 15 2013 - 10:24:12 EST


Reduce pointer reloading and improve locality-of-reference;
allocate read_buf and echo_buf within struct n_tty_data.

Signed-off-by: Peter Hurley <peter@xxxxxxxxxxxxxxxxxx>
---
drivers/tty/n_tty.c | 25 +++++++++----------------
1 file changed, 9 insertions(+), 16 deletions(-)

diff --git a/drivers/tty/n_tty.c b/drivers/tty/n_tty.c
index b8851b6..3daf9f0 100644
--- a/drivers/tty/n_tty.c
+++ b/drivers/tty/n_tty.c
@@ -105,9 +105,9 @@ struct n_tty_data {
unsigned char lnext:1, erasing:1, raw:1, real_raw:1, icanon:1;

/* shared by producer and consumer */
- char *read_buf;
+ char read_buf[N_TTY_BUF_SIZE];
DECLARE_BITMAP(read_flags, N_TTY_BUF_SIZE);
- unsigned char *echo_buf;
+ unsigned char echo_buf[N_TTY_BUF_SIZE];

int minimum_to_wake;

@@ -1694,9 +1694,7 @@ static void n_tty_close(struct tty_struct *tty)
if (tty->link)
n_tty_packet_mode_flush(tty);

- kfree(ldata->read_buf);
- kfree(ldata->echo_buf);
- kfree(ldata);
+ vfree(ldata);
tty->disc_data = NULL;
}

@@ -1714,7 +1712,8 @@ static int n_tty_open(struct tty_struct *tty)
{
struct n_tty_data *ldata;

- ldata = kzalloc(sizeof(*ldata), GFP_KERNEL);
+ /* Currently a malloc failure here can panic */
+ ldata = vmalloc(sizeof(*ldata));
if (!ldata)
goto err;

@@ -1722,16 +1721,14 @@ static int n_tty_open(struct tty_struct *tty)
mutex_init(&ldata->atomic_read_lock);
mutex_init(&ldata->output_lock);

- /* These are ugly. Currently a malloc failure here can panic */
- ldata->read_buf = kzalloc(N_TTY_BUF_SIZE, GFP_KERNEL);
- ldata->echo_buf = kzalloc(N_TTY_BUF_SIZE, GFP_KERNEL);
- if (!ldata->read_buf || !ldata->echo_buf)
- goto err_free_bufs;
-
tty->disc_data = ldata;
reset_buffer_flags(tty->disc_data);
ldata->column = 0;
+ ldata->canon_column = 0;
ldata->minimum_to_wake = 1;
+ ldata->num_overrun = 0;
+ ldata->no_room = 0;
+ ldata->lnext = 0;
tty->closing = 0;
/* indicate buffer work may resume */
clear_bit(TTY_LDISC_HALTED, &tty->flags);
@@ -1739,10 +1736,6 @@ static int n_tty_open(struct tty_struct *tty)
tty_unthrottle(tty);

return 0;
-err_free_bufs:
- kfree(ldata->read_buf);
- kfree(ldata->echo_buf);
- kfree(ldata);
err:
return -ENOMEM;
}
--
1.8.1.2

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